<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<style>
  div>div {
    background-color: red;
    min-height: 100px;
    min-width: 100px;
  }



  table {
    border: 10px solid lightgray;
    background-color: lightgray;
    border-collapse: collapse;
  }
  tbody {
    background-color: white;
    border: 1px solid black;
  }
  table th , td{
    border: 1px solid black;
    margin: 0;
  }
</style>

<body>

  <div>
    <div>demo</div>
    <div>table

      <P>
        {table}
      </P>

      <table >
        <tr>
          <th>Month</th>
          <th>Savings</th>
        </tr>
        <tr>
          <td>January</td>
          <td>$100</td>
        </tr>
        <tr>
          <td>February</td>
          <td>$80</td>
        </tr>
      </table>
    </div>
  </div>
  <script>

    const reg = /\<style\>$/;
    const styleStr = `<style>
  div > div {
    background-color: red;
    height: 100px;
    width: 100px;
  }
</style>`;


    const handleHtml = (getHtml) => {
      return `${getHtml()} ${styleStr}`
    }
  </script>
</body>

</html>